The invention concerns a milling drum and a construction machine, as well as a gearbox unit for a milling drum.
It is often necessary, due to varying job site situations and milling operations, to adapt the milling tool of a road milling machine to the specific tasks at hand. A milling drum with a particular spacing of the cutting tools or a different tooling is required when, for instance, a specific surface texture is to be achieved. In another application, only specific carriageway widths are to be removed, which requires a milling drum with a particular working width.
As a rule, a special milling machine has to be employed in these situations, or else the machine must be equipped with a milling drum adapted to the task at hand. Exchanging the milling drums presently involves a lot of effort, however, and requires special aids for the assembly or disassembly of the milling drum.
Milling drums for road milling machines or recyclers are known from EP 1194651 B and EP 1520076 B where the milling drum displays an interchangeable milling tube with the axis of the said milling tube being supported, by means of a support ring, on a support ring mount of a rotating body coupled to a milling drum drive. The support ring sits on the support ring mount with a predetermined play where dirty water, dust and fine particles of the road surface can penetrate the gap between the support ring and the support ring mount, in particular due to relative movements between the support ring and the support ring mount resulting from the milling operation. The capillary attraction of the clearance fit intensifies this effect, so that dirty water and fine-grained particles penetrate the fit.
When the milling tube with the support ring is to be pulled from the support ring mount for the purpose of disassembly, this is often very difficult or not possible at all.
Disassembly is not easy in view of the given dimensions, namely with a support ring that is short in relation to the diameter of the milling drum when seen in axial direction, even though the assembly in a cleaned state can also prove to be difficult due to tilting.
Supporting surfaces of conical design have also turned out not to be practicable as they can, on the one hand, settle too strongly and, on the other hand, display excessive radial play when the milling drum to be pushed on is too short. A conically designed supporting surface would, therefore, require the conical support ring and support ring mount to be positioned within an accuracy range of +/−1 mm in order to enable a function at all, in which case the problem of a conical connection being prone to seizing will persist nevertheless.
The purpose of the invention is, therefore, to simplify the assembly and disassembly of the milling tube in milling drums with interchangeable milling tubes, in construction machines with milling drums and in gearbox units driving a milling drum.
The characteristics of this application serve to provide a solution to this purpose.